Machine tool control arrangement



Patented Feb. 16, 1 1937 MACHINE TOOL CONTROL ARRANGEMENT Othmar Pollok,Berlin-Wilmersdorf, Germany,

asslgnor to General Electric Company, a corporation of New YorkApplication January 28, 1936, Serial No. 61,236 In Germany March 11,1935 1 Claim.- (Cl. 172-240) The present invention relates to machinetool control arrangements and has for its object to provide an improvedconstruction and arrangement for controlling machine tools.

For a consideration of what I believe to be novel and my invention,attention is directed following description and the claim appendedthereto in connection with the accomp drawing.

tothe anying The drawing illustrates diagrammatically a machine toolarrangement embodying my invention.

The arrangement comprises a machine tool having a reciprocating element,in the present instance, shown in the form of a table Ill .The

table which may be a part of a planing machine is moved back and forthbetween fixed points.

The drive mechanism for efiecting movement of the table includes a rackl l secured to the table and driven through a gearing l2 from a motor13, in the present instance indicated as a three-phase alternatingcurrent induction motor connected to a source of three-phase alternatingcurrent Hi. The connection includes a conductor l5 connecting one phaseof the motor directly to one phase of the three-phase alternatingcurrent line and conductors l6 and I1 connecting the other phase of themotor to the other phases of the alternating current line through theintermediary of reversing switching means. means include two switches l8and I9.

These switching In the present instance the switch 16 is closed and theswitch l9 open.

By reversing these switches,

that is, by opening the switch 18 and closing the switch I9 thedirection of rotation of the motor is reversed. I This reversing must beeffected at the end of each movement of the table i 0, that is, as thetable is moved towards the left the drive mechanism or at least a partthereof must be stopped in the end position and put in reverse positionto cause movement of the table in the opposite direction.

This is accomplished by the provision of a control mechanism forautomatically opening and closing the switches l3,

[6. This control mechanism comprises a movable support, in the presentinstance in the form of a. disk 20 which is rotatably supported anddriven through a belt 2| and a pulley 22,

, which latter forces the belt into contact with a portion of themachine table l0 and thereby establishes a friction drive of the disk bythe table. A source of light 23 is mounted on the movable support ordisk 20 and energized from the A-C line ll through conductors 24 andslip rings 25 secured to the disk 20. Photo-electric means, in

'nected to an amplifier 21, at which time the position the presentinstance two photo-electric cells 26 and 21, secured to adjustable arms28 and 23 respectively are disposed adjacent the disk 26 so that duringrotation of the latter the light from the source 23 alternately triccells 26 and 21. More specifically the photoelectric cells are adjustedso that they arestruck by the light of the source 23 in fixed positions,that is, the desired end positions of the table ill. The photo-electriccells are held in position by 10 means including a nut 30. The cell 26is con- 3l which is arranged to energize a relay 32 having a coresecured to the switch 16, and the cell 21 is connected through anamplifier 33, which latter energizes a relay 34 having a core secured tothe switch 18. The arrangement includes a holding circuit for eachrelay. The holding circuit for the relay 32 has contacts 35 incooperative relation with a contact-making member 36 secured to theswitch I8 and the holding circuit for the relay 34 has contacts 31 whichare closed by a contact-making member 38 secured to the switch 13. i Theoperation is as follows: Let us assume that with the switch l8 closed,the table is moved towards the right, as indicated by an arrow. Underthis condition the disk 20 is rotated in. clockwise direction, causingmovement of the light source 23 towards the photo-electric cell 26. Theadjustment of the latter is such that it is struck by the light from thesource 23 as soon as the table Ill reaches its right-hand end position.When this occurs, the photo-electric cell 26 closes a circuit in theamplifier 3i and effects through the latter energization of the coil ofthe relay 32 whereby the core of this relay is moved upward and effectsclosing of the switch I9 and at the same time breaks the holding circuitthrough contacts 31 and the contact-making member 38 for the switch l8and thereby effects 49 opening of the latter. Opening ofthe switch 18 inturn causes closing of the contacts 35 by the contact-making member 36and thereby establishes a holding circuit for the relay 32. The motorthen is rotated in reverse direction, caus- 5 ing movement of the table10 towards the left until the light 23 strikes the photo-electric cellof the switches is again reversed. It will be readily understood thatthe length of movement, that is, the stroke 50 of the table 16, may beadjusted by adjustment of the arms 23, 29 carrying the photo-electriccells 26, 21. In a preferred embodiment the arrangement is such that fora full stroke of the table the two cells 26, are about 60 angularstrikes the photo-elec- 5 degrees apart, in which case the light som'ce28 is tto'necl eloout too angular degrees for each. table movement.

The invention is not restricted to the form illustrated in the drawingwhich has been select eol only on account oi its simplicity To renderthe arrangement easily accessible and protected from dirt and injury, itmay he deslmhle to place the dick, together with the photo=electriccells, Within a loox located. on or near the machine heel plate. Eh thisconnection, the transmission of the tehle movement involves nodifflcvlty. The Whole device preferably mounted apart from the machinein as for as the movement of the table can he mechanically transmittedto the control apparatus. The invention can also he epnllecl to othei'kinds oi machines and other working operations. Y

Hot/ins; described the method of operation of my invention, togetherwith the apparatus which 1 now consider to represent the zest embodimentthereof, 1 desire to have it understood, that eoi/mee apparatus shownonly illmtrotecl end that the invention may he carried out Toy othermeans.

l/"J'hot I claim as new and desire to secure by Letters Patent of theUnited States, is:

Moclil'oe tool control arrangement including the comb lotion oi amachine tool hot 15: o re cl oroce table, a drive means lncluoll tor forthe table, reversing means for and income for octuoting the revere meansone] lot controlling" the stroke of the able, said means comoms hg tosingle source of l a rototehle shop for the source, o friction drive forrote g the support in i'esponee to move-- ment oi." the table, at leasttwo ohoto electric cells mowoteol atljostably towards eech ot er anddisposed adjacent the support cool in coo oemtive relation With thesource of light to @LLUSE the light ll on one cell in one cool pool oithe table 9 on to the other celllh oooo tloh of e tohle ohcl amplifies.mesh circuits including the cells.

UTE-HEAR Piil lhlmltli.

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